Method and Apparatus for Mitigating the Effects of Cross Correlation in a GPS Receiver
First Claim
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1. A method for acquiring or tracking weak satellite vehicle (SV) signals in the presence of strong SV signals by mitigating the cross correlation of a received signal from a strong SV and a clear/acquisition (C/A) code of a received signal from a weak SV, comprising:
- estimating the strong SV signal;
subtracting the estimated strong SV signal from the actual received signal from a weak SV; and
performing correlation of the subtracted signal with the C/A code of the weak SV.
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Abstract
A positioning system receiver that mitigates cross correlation of received signals from positioning system satellite vehicles by generating the strong satellite vehicle signal and subtracting it from the received signal before correlation while eliminating the need for cross correlation signature without changing the C/A code.
53 Citations
30 Claims
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1. A method for acquiring or tracking weak satellite vehicle (SV) signals in the presence of strong SV signals by mitigating the cross correlation of a received signal from a strong SV and a clear/acquisition (C/A) code of a received signal from a weak SV, comprising:
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estimating the strong SV signal; subtracting the estimated strong SV signal from the actual received signal from a weak SV; and performing correlation of the subtracted signal with the C/A code of the weak SV. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A GPS position signal receiver, comprising:
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an input sample memory in receipt of digital samples of positioning signals from at least two satellite vehicles (SVs); a carrier numerical controlled oscillator that generates a carrier offset signal; a complex mixer that combines digital samples from the input sample memory and the carrier offset signal from the carrier numerical controlled oscillator and results in a baseband signal; a strong satellite reconstruction module that generates an estimated strong SV signal; and a signal combiner that subtracts the estimated strong SV signal from the base band signal prior to filtering the baseband signal with a matched filter having a weak SV pseudo random number (PRN) as an input. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A computer-readable medium containing controller-executable instructions that when executed result in a method for acquiring or tracking weak SV signals in the presence of strong SV signals by mitigating cross correlation of a received signal from a strong SV and the C/A code of a received signal from a weak SV, the controller-executable instructions comprising instructions for:
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estimating the strong SV signal; subtracting the estimated strong SV signal from the actual received signal from a weak SV; and performing correlation of the subtracted signal with the C/A code of the weak SV. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification